This invention relates to apparatus utilizing a plurality of packed endless roller chains capable of moving independently with respect to each other, which chains over a portion of their travel are separated and in another portion come together into a common plane in general, and more particularly to apparatus for preventing the chains from running up upon one another as they enter into the common plane.
A particularly important application for a plurality of packed endless roller chains arranged side by side is in the type of continuous press apparatus described in U.S. Pat. No. 3,851,685 issued to K. Ahrweiler et al on Dec. 3, 1974. In the apparatus disclosed therein, an advancing web which starts out as a plurality of wood chips or the like is conducted through the press and formed into wood chip board or a similar product. In the apparatus the web is conducted between endless conveyor belts which both revolve moving along with the web which is conducted therebetween. Pressure is applied to the conveyor belts by means of support structures, one being disposed above and one below the web of material. The conveyor belts have a width equal to that of the web and there are disposed between the support structures above and below and the two conveyor belts, two sets of closely packed roller chains with the individual chains in each group capable of moving independently with respect to other chains in the group.
The chains are used to transmit pressure from the support structure to the conveyor belts. In the apparatus disclosed the chains, after leaving the pressing area of the press, return through the support structure in channels arranged in two different planes parallel to the plane of the web.
The roller chains each contain a plurality of adjacent rollers per link with the links connected by plates disposed only on the inside between adjacent rollers. In other words, the outer rollers of each link are cantilevered on the roller pin. This permits adjoining roller chains to be directly adjacent to each other to obtain a uniform rolling action over the entire pressure area of the press. Such uniform rolling is further assured by the chain construction shown in FIGS. 9-11 of that patent in which the individual rollers of a link are offset with respect to adjacent rollers to avoid the formation of elongated gaps between rollers.
In the apparatus described in the aforementioned patent, the roller chains are returned from the end of the pressure section to its beginning through a return plate which is disposed within the support structure for the conveyor belt. The chains return through slots extending in the travel direction within the support structure. Because the roller chains are immediately adjacent, the slots cannot be arranged in a single plane, [otherwise the pressure could not properly be transmitted]. Instead, they are disposed in two planes parallel to the plane of the web. When the roller chains arrive back at the beginning of the pressure section, they must be returned from the two planes into a single plane before entering the pressure section. Because the roller chains have a certain amount of mobility and are immediately adjacent, it is possible for rollers of adjacent chains to run with their edges up on to the edges of the rollers of an adjacent roller chain as they re-enter the common plane. Although in the further course of movement they may slide off, the proper running of the roller chains is adversely effected to a considerable degree by such interference of one chain with the other.
The same problems can occur in other apparatus than the type of press disclosed in the aforementioned patent. Essentially, this can be a problem in any type of device using a plurality of closely spaced chains. For example, there are types of apparatus where over a certain area chains are caused to leave a common plane because of the individual action of separate chain tighteners on each of the individual chains. In this case also, the chains must again at some point enter a common plane and the same problems can occur.
In view of these difficulties, the need for an improved apparatus for preventing the edges of adjacent chains from rolling up onto one another as the chains re-enter a common plane becomes evident.